000
FXUS63 KOAX 032320
AFDOAX
Area Forecast Discussion
National Weather Service Omaha/Valley NE
520 PM CST Sat Dec 3 2016
.SHORT TERM...(tonight through Tuesday)
Issued at 256 PM CST Sat Dec 3 2016
Isentropic ascent on the 285-295 K surfaces ahead of a positively
titled shortwave trough /located from eastern SD into central NEb
per afternoon water vapor imagery/ continues over eastern
Nebraska and western Iowa. This forcing is expected to continue
this evening until the axis of the trough shifts east after
midnight. For the most part the precipitation has fallen as light
snow with some light rain on the western and southern edge. The
majority of the light snow is melting on contact this afternoon,
but in a narrow band from LNK to the southern OMA metro area the
rates have overcome the melting, and up to a half inch has been
reported. In this band we may see up to an inch or slightly more
before the precipitation shifts off to the east. We will slightly
see some slick spots on roads, especially secondary roads within
this band. Temperatures through the event are expected to be near
or slightly above freezing, which should help mitigate some of the
impacts.
Once the trough shifts to the east we will see clearing skies on
Sunday with winds become west and northwest through the day, which
should lead to decent mixing and warmer temperatures with highs
climbing into the 40s for many areas. Another shortwave trough
will quickly move through the northern Plains on Monday allowing
for a strong cold front to sweep through the CWA late in the day
and into Monday evening. Moisture will be limited to the southern
Plains associated wtih the ejection of the current closed low, but
strong low-level frontogenesis may allow for some flurries or a
brief period of light snow across western Iowa just behind the
front.
.LONG TERM...(Tuesday night through Saturday)
Issued at 256 PM CST Sat Dec 3 2016
The global models are now in good agreement for mid to late week,
and confidence in the sensible weather is much higher today. The
front on Monday night should continue south into the southern
Plains while additional jet energy quickly shifts through the
Great Basin. This will translate east through the Plains along the
preexisting strong thermal gradient. This should lead to a zone of
stronger frontogenesis and a band of light snow in the Plains for
late Tuesday night and into Wednesday. Currently is appears that
this band will mostly be south of the FA, but we will continue to
indicate some low-chance pops over the southern CWA due to the
uncertainty in the placement at this range.
The more significant story though is expected to be the cold air
with a second cold front that will move through the area on
Tuesday night. This will bring the coldest air of the new season
to the region to end the work weekend into the weekend. Both the
GFS and EC indicate the next shortwave trough and associated
chance for precipitation, likely in the form of light snow, is
expected toward next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 520 PM CST Sat Dec 3 2016
Mosaic radar data as of 23z revealed a band of light to
occasionally moderate snow located along and just to the south of
I-80 where observed visibilities were 3/4 to 1 1/2 miles. Expect
similar snow rates at KLNK and KOMA for the next few hours before
the broader-scale precipitation shield begins to shift east ahead
of a mid-level trough translating across the northern and central
Plains. Even with the cessation of precipitation
tonight...ceilings and visibilities are not likely to increase
owing to fog formation which will persist into Sunday morning.
Conditions should begin to improve thereafter as a weak front
moves through the area. At KOFK, IFR ceilings are likely to
persist into early Sunday with some visibility restriction due to
fog.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
SHORT TERM...
LONG TERM...
AVIATION...Mead